Research And Design Of Gypsum Ore Mining Method Based On Blasting Damage

There is obvious group pressure and rock blasting damage when exploring the-580 m seam of Dahan mine of Lanling gypsum group. Also, it is difficult to meet the requirements of safe production with traditional experience analogy. In this paper, the geological conditions, the rock properties and the present mining situation of the mine are investigated, and the blasting disturbance test has been done in laboratory and field to study the damage law and weakening effect of surrounding rock caused by blasting.Then the physical and mechanical parameters of rock is determined based on the test results. This paper employs FLAC3 D numerical simulation software to design the stope structure parameters and analyze the stability of stope structure. In this way, the mining method, the layout of stope of-580 m level of Dahan gypsum mine can be determined.The field test takes the form of the small blasting and the sonic wave cross hole test. The results show that the blasting influence depth of surrounding rock is about 175cm~225cm; And not every blasting produces macroscopic damage to the rock. Sometimes local fracture closure or consolidation may occur; The blasting damage is relatively large in the bearing area of the surrounding rock.Based on the frequency, the peak vibration velocity, and the vibration duration data measured in gypsum mine, the blasting damage laboratory test are conducted under 40%, 60% and 80% level of uniaxial compression of the gypsum specimen. The result shows that the damage law of gypsum under disturbing load in different static load level concides with logarithmic function; The lowest coefficient of the gypsum specimen`s integrity is 0.64 after 50 times disturbance under the 80% uniaxial compressive strength level.Based on the test results of blasting damage, we reduce the rock parameters to determine the parameters of rock mass. Then the “beam” theory of mechanic of materials and FLAC3 D numerical simulation are adopted to determine the parameters of stope structure; The critical theory of strength and FLAC3 D dynamic stress analysis are employed to evaluate the stability of the mine goaf. This paper finally settles for the layered shallow hole room and pillar mining method.Adopting this method, The seam is divided into 2 segments with 8m mining height,5m width, 50 m length, and the width of the pillar is 8m in each sublevel with a1.5mprotection top, a 1m protection bottom and a 5m interlayer pillar.